Communications: electrical – Systems – Selsyn type
Reexamination Certificate
2000-02-03
2001-08-21
Pope, Daryl (Department: 2632)
Communications: electrical
Systems
Selsyn type
C340S534000, C340S538000, C340S315000, C340S315000
Reexamination Certificate
active
06278357
ABSTRACT:
BRIEF DESCRIPTION OF THE INVENTION
This invention relates generally to the utilization of electrical utility power lines. More particularly, this invention relates to a technique for transmitting and receiving digital information within an electric utility power line network.
BACKGROUND OF THE INVENTION
Power line networks interconnect practically every home and business in the United States. It would be highly desirable to utilize this established infrastructure to deliver digital information. A system of passing digital information over power line networks could be exploited in a large number of ways, including: remote meter reading, load control, status checks on switches and related electrical equipment, telemetry, and the like.
Prior art attempts to implement digital communications over power line networks have met with limited success. One problem with prior art systems is that they have relatively low data rates. In many systems, this problem is attributable to the fact that digital information can only be placed at limited locations on a carrier power signal. Another problem with prior art systems is that they can only send information in one direction. For example, some systems can only push information “upstream” from a distribution location to a substation location, but cannot pass information “downstream” from a substation location to a distribution location. Thus, bi-directional communication is not possible. Another problem with prior art systems is that they require the installation of supplemental, specialized equipment on the power line network. Examples of such equipment include signal repeaters and capacitor blocking reactors.
In view of the foregoing, it would be highly desirable to provide an improved system for implementing digital communications in a power line network.
SUMMARY OF THE INVENTION
The apparatus of the invention establishes bi-directional digital communication over a power line network. The apparatus includes a signal launching circuit to impose a digital communication signal onto a power signal carried by a power line network and thereby form a digital communication power signal at a first point in the power line network. The signal launching circuit is configured to position a pulse of the digital communication signal at any phase location of each half cycle of the power signal. A receiver reads the digital communication power signal at a second point in the power line network. A signal processor is connected to the receiver to recover the digital communication signal from the digital communication power signal.
The method of the invention includes the step of imposing a digital communication signal onto a power signal carried by a power line network and thereby forming a digital communication power signal at a first point in the power line network. The imposing step includes the step of selectively positioning a pulse of the digital communication signal at any phase location of each half cycle of the power signal. At a second point in the power line network, the digital communication signal is recovered from the digital communication power signal.
The invention successfully operates on existing distribution system wiring, without requiring the installation of signal repeaters or reactive coupling or blocking devices. The invention provides a bi-directional communication system that is relatively low cost from an installation and maintenance perspective. The communication equipment and protocol associated with the invention are under complete cost and operating control of electric utility personnel. The invention obviates the need to provide broadband technologies for low bandwidth applications, such as automatic meter reading, distribution automation, and home security. This bi-directional communication system provides a highly functional, secure, and reliable path to an electric utility customer.
REFERENCES:
patent: 4755792 (1988-07-01), Pezzolo et al.
Childers, IV James M.
Croushore Timothy M.
Curt Walter M.
Guyker William C.
Mullins Chris F.
Electric Power Research Institute Inc.
Pennie & Edmonds LLP
Pope Daryl
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